First Order Predicate Logic vs The Judeo-Christian creator

[Tiberius]

Either something exists and belongs in the {exists} set... or it doesn't and it belongs in the {no/exist} set.

I got that, and I didn't use it incorrectly. Perhaps you are unfamiliar with set notation?

{exist} \ {God} means "Everything in the set of existing things minus the subset containing God". So {exist} \ {God} + {God} = {exist} simply states that the set of everything that exists apart form God, plus God, equals the set of everything that exists. It is the same as saying: 2 - 1 + 1 = 2

using god as a seperate set outside of the other two sets doesn't work...

Well it does if you aren't breaking the rule that everything has to be in one set of the other. How else can you reference specific items of either set?

My point of contention is that you are arguing that everything in {exist} must already exist at the beginning, and therefore God cannot possibly have created everything in the {exist} set. You ignore the common Christian belief that God created (brought into existence) everything.

Thus, at the "beginning":

{exist} = {God} (The only thing existing was God)
{no/exist} = Every possible thing that does not exist.

God, being supposedly all-powerful, then moves items from the set of {no/exist} into the set of {exist}. So, say for example that God creates man:

{exist} = {exist} U {man}
{no/exist} = {no/exist} \ {man}

In the first step, God puts {man} in the {exist} set, since he now exists. He simultaneously (so as not to break your rule) removes {man} from the set of {no/exist}.

If existence is eternal, why need a God? Wouldn't things pretty much sprout on their own sooner or later with an infinite amount of time?

Existence isn't actually a thing though. Existence itself doesn't belong in the set {exists} since it would be contradictory. Existence is an attribute of the system, nothing else. The very system was set up so as to preclude existence, otherwise you could not come up with the rules he set out at the beginning (that everything that exists belongs in {exist}, and everything that doesn't is in {no/exist}). If there is nothing that exists that can bring things into existence, how do expect things to move out of the {no/exist} set into the {exist} set?

Also, who created existence if God is subject to it?

See above. Existence is an attribute (and a subjective one at that). It is an attribute of the system used to describe relationships between the {exist} and {no/exist} sets, not an object in the set.